Sound-reproducing device and adjusting means therefor



April 3, 1928.

s. R. SWENSON SOUND REPRODUCING DEVICE AND ADJUSTING MEANS THEREFOR Filed Aug. 26, 1924 32 17 11 K \i' 35 3Q 31 um w ll 34 30 INVENTOR BY v M}- M ATTORNEY s- Patented Apr. 3, 1928.

UNITED STATEfi .oFFlcE.

.SWEN R. SWENSON, OF SOUTH ORANGE, NEW] JERSEY, ASSIG-NOR T0 MULTIPLE ELEC- TRIO PRODUCTS) COMPANY, INC., OF NEVI YORK, N. Y., A CORPORATION OF NEW YORK.

SOUND-BEPRODUCING DEVICE AND ADTUSTING MEANS THEREFOR.

Application filed. August 26, 1924. Serial No. 734,213.

This invention relates to devices for translating electric undulations into sound vibrations. More specifically it relatesto electromagnetic receivers of the diaphragm type and has for one of its objects to increase the efiiciency of operation of such devices.

Another object is to provide means for effectively and conveniently adjusting the dia phragm or diaphragms of a loud speaker.

Other objects and advantages will appear as the invention is hereinafter disclosed.

Referring to the drawings which illustrate what I now consider a preferred form of the invention:

Fig. 1 is a side elevation of a loud speak or embodying the features of my invention.

Fig. 2 is an enlarged sectional elevation of the device shown in Fig. 1 with the horn broken away.

Fig. 3 is an enlarged elevation, partly in section, of the device shown in Figs. 1 and 2.

Fig. 4 is an inverted detail plan view showing a part of the adjusting mechanism.

While the features of invention maybe applied to other receivers, such 2 as head phones, and employed for other purposes, they are particularly applicable to devices now known in the art as loud speakers and adapted to be employed in the reception of radio telephonesignals. Therefore, I have selected for the purpose of illustration a loud speaker, in order to disclose the features of invention. A form of loud speaker now preferred is illustrated in the drawings and may be constructed as follows:

The loud speaker comprises a casing 10 provided with a cap 11, which cap and casing enclose the diaphragm or diaphragms and the electromagnetic means for actuating the same. It will be noted that the casing 10 is provided with a flange 12,the peripheral edge of this flange being screw threaded at 13 to cooperate with threads provided on the inner wall of the cap 11, whereby the cap and easing may be detached from each other and whereby relative rotation of the cap and cover causes relative longitudinal ,movcment of said cap and cover.

The loud speaker comprises also a base 14 upon' which the device is adapted to rest, the

cap 11 being suitably secured to the base as by means of cooperating screw threads '15 provided on the exterior wall of the cap and electromagnets. is mounted in the cap 11 between the annular inner wall of the base. The cap 11 is provided with a central opening 16 into which the metallic ferrule 17 of amplifying horn 19 extends. Preferably the ferrule 17 is externally threaded at 18 to screw into the opening 16, the wall of the latter being tapped for that purpose. The horn 19 is preferably constructed of molded wood pulp, although other materials may satisfactorily be employed.

It will now be appreciated that the cap 11 supports the horn 19 above it and the casing 10 below it, and is in turn supported by the base section 14. I shall now proceed to describe the instrumentalities for translating the electric undulations into sound vibrations, all of these instrumentalities being located within the container formed by the casing 10 and cap 11.

The electromagnets 20, 20 (of which one of the pairs is shown in Fig. 2) and permanent polarizing magnet 21 common to devices of this general type and, except for changes in dimensions, to watch-case tele-- phone receivers, are mounted within the casing 10 and suitably secured therein. Any suitable means (not shown) may be employed for supplying the undulating current to the windings of the electromagnets 20, 20, A

diaphragm 22 of silicon steel, iron' or other suitable material is mounted across the open upper end of the casing 10 and is adapted to be vibrated by undulating currents in the A second diaphragm 23 shoulder 24 of the latter'and the diaphragm 22. Preferably an annular gasket 25'of rubber strip, or other suitable compressible material, is interposed between the shoulder 24 and the upper outer edge portion of the diaphragm 23. The diaphragms are spaced apart at their centers by a sleeve 26 of hard rubber or other suitable material, the diaphragm 22 having a struck-up teat 27 which extends into the sleeve 26 and the latter being preferably shellacked or otherwise secured to the brass washer 28 riveted'to the diaphragm 23 at the center thereof. It will be noted that the diaphragms 22 and 23 are of different diameters (the latter being the larger) so that the natural period of one diaphragm differs from that of the other. By virture of this construction more faithful reproduction of sound is obtained. The

faithfulness of reproduction may be still further increased by making the diaphragm 23 of micarta, impregnated fabric, or other suitable non-metallic material, the diaphragm 22 being constructed of magnetizable metal.

In the use of the instrument, the cap 11 and casing 10 are screwed relatively toward each other, therebycausing the circular discshaped diaphragms 22, 23 to bulge or conare located more remotely than others, and.

that other factors vary the desirability, if not the necessity of LClTfUStZHGIlt, and convenlent ad ustment of the diaphragm or diaphragms will be appreciated. A preferred form of adjusting means is shown in the drawings and may be constructed as follows:

The under side of the flange 12 of the casin 10 has secured thereto a circular rack or spur gear 80 adapated to mesh with a pinion 31 provided with a square central opening adapted to receive the squared portion 82 of a shaft 33,;journaled for rotation in a suitable opening in the upper partof the base 14. The pinion 31 is held on its shaftby means of a screw 36, a washer 37 being mounted between the pinion 31 and the head of the screw. The shaft 33 is provided with an enlarged portion 34: which, to-

, gether with the pinion 81, limits the endwise movement of the shaft. A- milled head 35 facilitates manual rotation of the shaft 33 and its pinion 31;

I When the device is assembled atthe factory the casing 10 and cap .11 are rotated with respect to each other until the best average adjustment of the diaphragm is ob tained. The cap 11 is also screwed tightly into the base 1 1 and, if desirable, cemented thereto by applying any suitable cement to the screw threads 15 before the cap is screwed home into the base. The pinion 31 is then mounted as shown in Fig. 2. The usermay now adjust the diaphragms simply by turning the knob 35 in the desired direction and to the desired extent. Obviously, rotation of the knob 35 causes rotation of the pinion 31,

the gear 30, and the casing 10, the. cap 11 remaining stationary with respect to the base 14;. In view of the fact that the gear 31 is much smaller than the gear 30, fine adjustments may be efiectedand inadvertent turning of the casing 10 is prevented.

In accordance with the provisions of the patent statutes, I have herein described the principle of operation of my invention, together with the apparatus which I new con sider to represent the best embodiments thereof, but I desire to have it understood that the apparatus disclosed is only illustrative and that the invention can be carried out by other means.

lVhat I claim is:

1. A loudspeaker comprising in combination, a casing and cap therefor, an electromagnet mountedwithin said casing, a pair ofdiaphragms spaced at their centers and mounted between said electromagnet and cap. meansfor causing said diaphragms to convex away from each other upon relative rotation of said cap and casing in a predetermined direction, a base to which said cap is securedand surrounding said casing, and means operable from the exterior .of said base for causing relative rotation of said casing and base. r

2. The combination set forth in claim 1, in which the last mentioned means comprises a gearsecured to said casing.

3. The combination set forth in claim 1. in which the last mentioned means comprises a circular rack secured to said casing, and an adjusting pinion of smaller radius meshing with said rack.

4. The combination set forth in claim 1, in which the last mentioned means comprises a circular rack secured to said casing, an adjusting pinion of smaller radius meshing with said rack, and a shaft for turning said pinion and extending through said base. g

5. A device for translating electrical undulations into sound vibrations and comprising in combination, a two-part casing, an electromagnet and diaphragm mounted within said casing, means for causing relative movement of said electromagnet and diaphragm toward and away from each other upon relative rotation of the twoparts of said casing, and mans comprising a gear wheel secured to one. of the parts of said casing and a manually operable pinion meshing with said gear wheel for causing relative rotation of the parts of said casing.

6. Adevice for translating: electrical undulations into sound vibrations and comprising in combination, a two-part casing, an electromagnet mounted within said casing, a pair of diaphragms spaced at their centers and mountedbet-ween said electromagnet and one of the parts of said casmg, means for causing said diaphragms to convex away from each other uponrelative rotation of the two parts of said casing in a predetermined direction, and means comprising a gear wheel secured to one of the parts of said casing and a manually operable pinion meshing with said gear wheel for causing relative rotation of the parts of said casing.

7. The combination set forth in claim 1, in which the natural period of one diaphragm is greater than that of the other.

8. The combination set forth in claim 6, in which the natural period of one diaphragm is greater than that of the other.

9. A loud speaker comprising in combination, a casing and cap therefor, an electromagnet and diaphragm mounted within said casing and cap and relatively movable toward and away from each other upon relative r0- tation of said casing and cap in opposite directions, a base to which said cap is secured and surrounding said casing, and means operable from the exterior of said base for causing relative rotation of said casing and base, said last mentioned means comprising a gear secured to said casin 10. A loud speaker comprising in combination, a casing and cap therefor, an electromagnet and diaphragm mounted within said casing and cap and relatively movable toward and away from each other upon rela tive rotation of said casing and cap in opposite directions, a base to which said cap is secured and surrounding said casing, and means operable from the exterior of said base. for causing relative rotation of said casing and base, said last mentioned means comprising a circular rack secured to said 7 casing and an adjusting pinion of smaller radius meshing with said rack.

11. A loud speaker comprising in combination, a casing and cap therefor, an electromagnet and diaphragm mounted within said casing and cap and relativel movable toward and away from each ot er upon relative rotation of said casing and cap in opposite directions, a base towhich said cap is secured and surrounding said casing, and means operable from the exterior of said base for causing relative rotation of said casing and base, said last mentioned means comprising a circular rack secured to said casing, an adjusting'pinion of smaller radius meshing with said rack, and a shaft for turning said pinion and extending through said base. 1

12. A loud speaker comprising in combination, a casing and cap therefor, an electromagnet and diaphragm mounted within said casing and capand. relatively movable to ward and away from each other upon relative rotation of said casing and cap in opposite directions, a base to which said cap is secured and surrounding said casing, said base being adapted to rest at its bottom on a flat supporting surface, and means including a part extending upwardly through the top of said base and operable from the exterior of said base for causing relative rotation of said casing and base.

In testimony whereof I hereto affix my signature.

SWEN R. SWENSON. 

